1. Field of the Invention
The present invention relates to methods and apparatus for the delivery of fragrances, perfumes, deodorizers, pest repellents, and other dispersants to surrounding environment.
2. Description of Related Art
Delivery of various dispersants to surrounding environments is an area of continuing interest. This procedure usually employs a solid, liquid, or gaseous dispersant which is placed into a gaseous or particulate form and delivered periodically or continuously to surrounding air. Of particular interest is the continuous delivery of dispersant from a stationary receptacle over an extended period of time. Among the dispersants commonly delivered in this manner are various scents of perfumes and similar fragrances, deodorizers, pesticides and pest repellents, corrosion inhibitors, moisturizers, desiccates, medicinal vapors, scented oils, "neat" oils (i.e., straight oil without admixture or dilution), etc. Examples of apparatus providing this function are illustrated in U.S. Pat. Nos. 1,129,897 issued Mar. 2, 1915 to Owen, Jr. (air moisturizer), 2,219,959 issued Oct. 29, 1940, to Laidley (container humidifier), 2,766,069 issued Oct. 9, 1956 to Tennyson (apparatus delivering corrosion inhibitor vapors), 3,169,705 issued Feb. 16, 1965 to Geiger (device for continuous emission of active substances), and 3,727,840 issued Apr. 17, 1973, to Nigro (dispersant container and dispenser).
A major problem with the delivery of certain dispersants over an extended period of time, particularly highly volatile chemicals such as "neat" oils, spiced oils, and oily/concentrated fragrances for deodorizing, is achieving a uniform delivery of the dispersant. All too often the rate of dispersant delivery begins excessively and then drops steadily or rapidly to an inadequate amount. This condition is due in part to the volatile nature of some dispersants which dispense their most volatile elements immediately and release less volatile elements at much slower rates. Additionally, if dispersion is through a wick or similar device, there is a tendency for residues to build-up in the wick and decrease its effectiveness over time at transferring dispersant. This condition can also lead to poor quality of fragrance and/or a change in the fragrance "note" (i.e., original scent) over time.
The inconsistent release of chemical dispersants is viewed as unacceptable in numerous respects. First, immediate release of excessive odor can be objectionable and, depending upon the dispersants employed, may be hazardous. Second, the operational life of the dispersant delivery system is severely restrained, both due to an initial waste of dispersant which eliminates its availability for long-term use and to limitations on the total quantity of dispersant emitting substance which can be placed within the dispersant delivery systems without causing extreme reactions to the initial chemical release. Third, an inconsistent dispersant release rate is wasteful and leads to premature disposal of the dispersant delivery system. Fourth, with the volatilization of various components at different rates, the original fragrance "note" can be readily lost or distorted.
Another serious problem in developing a successful dispersant delivery system is that certain harsh dispersants tend to attack some materials which might otherwise be effective at providing a uniform chemical delivery rate. Accordingly, chemical resistance remains a major concern in the development of any dispersant system.
In recognition of some of these problems, a number of partial solutions have been suggested. In U.S. Pat. No. 3,790,081 issued Feb. 5, 1974, to Thornton et al. a manually adjustable device is provided for delivering chemicals to surrounding atmosphere. This device contains adjustable openings which can be proportioned to increase or decrease the amount of dispersion of vapors from the device. While this device does permit adjustment of the amount of flow, it requires regular monitoring and manipulation in order to achieve a constant rate of chemical dispersion. Additionally, for many applications this device is considered too complicated and bulky to allow it to be economically and conveniently employed.
A compact, self-regulating device is disclosed in U.S. Pat. No. 4,413,779 issued Nov. 8, 1983, to Santini. This device employs a simple container with a wick and porous plastic cap element from which evaporation occurs. In order to regulate the rate of dispersion, an occluding agent (e.g. isoparaffinic and normal paraffinic solvent) is impregnated into the porous plastic element to control the rate of dispersion. While this device may experience improved control of the rate of dispersion emission, more regular and better controlled dispersion is believed possible. Moreover, the use of paraffin is believed to seriously limit the chemical resistance of this device. Additionally, a still more compact and durable receptacle for the delivery of dispersant is likewise desired.
Another approach is shown in U.S. Pat. No. 4,917,301 issued Apr. 17, 1990, to Munteanu. In this device a container of liquid volatile substance is provided with an opening covered with a microporous membrane such as a non-woven polyester sheet. While this device may provide somewhat improved transfer of dispersant and may experience decreased contaminant build-up, a more consistent and linear rate of dispersion of dispersant continues to be sought. Another problem with this system is that it is limited in its chemical compatibility and may not be suitable for certain dispersants, such as very strong oils.
Another approach is taken in Japanese Laid-Open Patent Application JP 4-132556, laid open May 6, 1992. This patent is directed to a deodorizing bag filled with deodorant gel, sol or liquid and constructed from an air permeable and water impermeable material, such as polyethylene porous film, tetrafluoroethylene resin porous film, polyethylene terephthalate nonwoven cloth, or nylon nonwoven cloth. The deodorizing bags are durable and of minimal size, which allows them to be freely used in a wide variety of applications. Unfortunately, based upon the materials used in these bags they would be expected to suffer from the same inconsistent dispersion performance over time as the apparatus previously discussed.
Accordingly, it is a primary purpose of the present invention to provide a dispersant delivery apparatus and method which automatically delivers a relatively consistent level of chemical dispersant over the life of the apparatus.
It is a further purpose of the present invention to provide such an apparatus and method which can be formed of minimal size and complexity so as to provide dispersant delivery to many different applications.
It is another purpose of the present invention to provide an apparatus and method for dispersant delivery which employs a durable casing and transfer membrane so as to allow its use with a wide variety of dispersant materials and in many different environments.
These and other purposes of the present invention will become evident from review of the following specification.